" not many feel comfortable with that"

Most people are taught to back off the rpm to 2500 and the MP to 32" upon reaching pattern altitude.    My rationale for maintaining the high setting is that if you are full rich, the maximum internal cylinder pressure is less, even at 38" than it is if you are only somewhat (75-100 ROP) at 32".   ....and also being higher RPM makes the angle of maximum pressure further after TDC.    ....and I think George Braly agrees.

However, I don't have my "exceeded TBO" proof of the pudding yet.

Bob, how many hours on your engine now?

Colyn

On Jun 13, 2011, at 4:29 PM, Bob Rickard wrote:

I am a 4P TSIO 550E guy.  I don't have a plenum.

I personally use the climb technique mentioned below every time I fly, as I am usually flying long distance (> 1000nm).  I takeoff full power (38.5MAP, 43-45gph, 2700 rpm) and keep that to the level off point, usually FL 180-220.  I then run 34" MAP, 2500 RPM, and lean 100deg LOP which usually results in 17-18 gph.  I don't touch the motor again until near the pattern and need to slow down.  My motor stays below 380 in the climb on all cylinders unless it's super hot out, at which point I level off for a few minutes half way up, let er cool down, then finish the climb.  My climb airspeed is 165 kcas to 15,000 then 160 the rest of the way.  I could climb faster, but the key is to get air over the motor.  Climb rate varies obviously with gross weight and temp, and is well over 1000 fpm, but it would not be if I climbed LOP.  I use this technique to get high and LOP as soon as possible, and routinely get 4.5 hours sortie duration or longer.

I am curious about the " not many feel comfortable with that" comment.  It's what I was taught and nobody has ever mentioned it is a "bad" technique.  Open to comments as to other techniques and why they are used.

Bob Rickard

On Jun 13, 2011, at 11:48 AM, Colyn Case <colyncase@earthlink.net> wrote:

The IVP will climb much faster but you have to have excellent cooling and very high fuel flow to do it.    George Braly did a seminar on engine cooling back a few years which I think is captured here in the archives somewhere.   My main take-aways on cooling:   you must have the exhaust tunnel extensions and you must insure that cooling air is guided around the bottom side of EVERY cylinder.    The fuel flow specification is in the TCM document but it ends up being 43+ gph at 38"/2700rpm.   

Put all that together and you can climb 2000 fpm at 140 knots and still be below 380 dF on the cylinders.    Not many people feel comfortable doing that though....

What power settings does a velocity need to do that?

Colyn

On Jun 13, 2011, at 7:50 AM, RONALD STEVENS wrote:

Wow, this was just a great answer, not based on emotions but just pure calculations. Like to add that I have seen that a lot of 4p owners do not go higher then 18000ft (VFR 17500), and that this might be also because the climb does take a long time.

I have sit in a few Lancair 4p's now and one thing I noticed is that the climb rate is not really that great. (1000-1400 fpm), while my old velocity easy did 1800-2000fpm (but at 145 IAS).

Now I understand you guys go faster (+/- IAS 160) but climbing then to Level 250 take about 23 min. (more or less, they never let you go direct, right?)

Anybody has better numbers or better climb performance tips?

From: Colyn Case <colyncase@earthlink.net>
Reply-To: Lancair Mailing List <lml@lancaironline.net>
Date: Sun, 12 Jun 2011 12:55:23 -0400
To: <lml@lancaironline.net>
Subject: [LML] Winglets? And introducing myself as a very near future 4p owner.

Another comment on winglets.

My theory is the most important speed is your SL speed.

Suppose you are flying 1350 nautical miles.

Westbound you have a 40 knot headwind at 5000 increasing to 100 knots at fl200.

Eastbound let's say you get a 40 knot tailwind at fl200.   (Doesn't it usually work out that way?)

Someone offers you mod A that gives you 10 knots at 5000 or mod B that gives you 10 knots at fl200.

...and let's say your plane does 225 knots at 5000 unmodified.

mod A gives you 10/(225-40) or 5.4% improvement which you enjoy for 6.9 hours

mod B gives you 10/(270+40) or 3.2% improvement which you enjoy for 4.2 hours

So even if the winglets delivered performance up high they don't seem like a very good deal.

Colyn

On Jun 7, 2011, at 2:18 PM, RONALD STEVENS wrote:

Hello guys.

 

I like to introduce myself, I am 50, European/American, former Cirrus

SR22 (1100 hours) and Velocity TXL5 (250 hours, just sold this plane)

(total 1400 hours).

 

I am a future Lancair 4p owner (looking to buy one these weeks, so if

you know someone who wants to sell his let me know) and looked at a few

Lancair 4p already.

 

Now about the winglets (my first question);

Some planes I looked at had their winglets, some not. All those that did not had one told me it doesn't do anything, the ones they had did told me it works great,

more stability etc, even the CAFE report is telling that it produces

more stability at higher altitude.

 

But…even the big Charlie Kohler told me it doesn't add anything but more

drag...thus less speed.

 

I have no experience whatsoever with the Winglets. So my question to you

guys is, do you have any experience telling you that it does work? (this

is more for pilots who had both so they can tell the difference)

 

Thanks -- Ronald Stevens

 

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